Re: BGP+Label issue

From: Tony Singh <mothafungla_at_gmail.com>
Date: Wed, 24 Sep 2014 00:36:42 +0100

Ahh beat me to it, reason is the pre-calculated CEF entry for the MPLS label plus ethernet frame is not bound to a /32 host route, in IOS this happens by default in XR it doesn't , why it doesn't do this beats the life outta me it's something Cisco is aware of and even in the 5.2.0 train they don't fix it, can someone more informed let me know why?

--
BR
Tony
Sent from my iPad
> On 4 Aug 2014, at 21:26, Maarten Vervoorn <mr.vervoorn_at_gmail.com> wrote:
> 
> Hi Group,
> 
> It helps when you write things down. I solved th issue. I needed to add a
> static /32 route for the next-hop for it to allocate a label
> 
> router static
> vrf ABC
>  address-family ipv4 unicast
>   172.2.38.3/32 GigabitEthernet0/0/0/0.38
>  !
> 
> Maarten
> 
> 
> 2014-08-04 22:15 GMT+02:00 Maarten Vervoorn <mr.vervoorn_at_gmail.com>:
> 
>> Hi All,
>> 
>> I'm practising on the Cisco CCIE Sample lab for service provider.
>> 
>> https://learningnetwork.cisco.com/servlet/JiveServlet/download/149550-38956/CCIE%20SP%20v3.0%20Sample%20Lab%20Part%20-%204%20of%207.pdf
>> 
>> I encountered on a issue with the CSC configuration specifically with BGP
>> plus label between R3 (IOS) and R8 (XR). I have configured LDP between R7
>> and R1. R8 and R7 are two of the backbone routers and serve as PE to R1 and
>> R3.
>> 
>> With BGP+Label configured between R3 and R8 I cannot get up communication
>> between R1 and R3 loopback interfaces. As soon as I remove the BGP+label
>> config  reachablility is restored. When I debug with BGP+Label activated I
>> can see R3 is able to reach out to R1 but when R1 sends packets back to R3
>> it gets dropped on R8. R7 has VPN label 16008 in it MPLS forwarding table
>> this is also listed as local label on R8. But R8 drops the packet because
>> it has no LFIB entry.
>> 
>> R1 loopback 172.2.0.1
>> R3 loopback 172.2.0.3
>> 
>> See below the MPLS forwarding table of R7
>> R7#sh mpls forwarding-table
>> Local      Outgoing   Prefix           Bytes Label   Outgoing   Next
>> Hop
>> Label      Label      or Tunnel Id     Switched
>> interface
>> 16         No Label   172.2.0.1/32[V] <http://172.2.0.1/32%5BV%5D>
>> 30269         Et0/0.17   172.2.17.1
>> 17         Pop Label  2.2.0.2 279 [4]  0             Et0/0.79
>> 2.2.79.9
>> 19         Pop Label  2.2.0.2/32       0             Et0/0.27
>> 2.2.27.2
>> 20         Pop Label  2.2.0.8/32       15100         Et0/0.78
>> 2.2.78.8
>> 21         Pop Label  2.2.0.9/32       645           Et0/0.79
>> 2.2.79.9
>> 22         Pop Label  2.2.28.0/24      0             Et0/0.27
>> 2.2.27.2
>>           Pop Label  2.2.28.0/24      0             Et0/0.78
>> 2.2.78.8
>> 23         Pop Label  2.2.29.0/24      0             Et0/0.27
>> 2.2.27.2
>>           Pop Label  2.2.29.0/24      0             Et0/0.79
>> 2.2.79.9
>> 24         24         2.2.0.8 89 [9]   484480        Et0/0.27
>> 2.2.27.2
>> 26         Pop Label  172.2.17.0/24[V] <http://172.2.17.0/24%5BV%5D>
>> 0             aggregate/ABC
>> 27         16008      172.2.0.3/32[V] <http://172.2.0.3/32%5BV%5D>
>> 11520         Et0/0.78   2.2.78.8
>> 28         16011      172.2.0.5/32[V] <http://172.2.0.5/32%5BV%5D>
>> 0             Et0/0.79   2.2.79.9
>> 29         16014      172.2.0.12/32[V] <http://172.2.0.12/32%5BV%5D>
>> 732           Et0/0.79   2.2.79.9
>> 30         17         172.2.0.14/32[V] <http://172.2.0.14/32%5BV%5D>
>> 0             Et0/0.27   2.2.27.2
>> 31         16009      172.2.38.0/24[V] <http://172.2.38.0/24%5BV%5D>
>> 0             Et0/0.78   2.2.78.8
>> 32         16017      172.2.38.8/32[V] <http://172.2.38.8/32%5BV%5D>
>> 0             Et0/0.78   2.2.78.8
>> 33         16007      172.2.59.0/24[V] <http://172.2.59.0/24%5BV%5D>
>> 0             Et0/0.79   2.2.79.9
>> 34         16018      172.2.126.0/24[V] <http://172.2.126.0/24%5BV%5D>   \
>>                                       0             Et0/0.79
>> 2.2.79.9
>> Local      Outgoing   Prefix           Bytes Label   Outgoing   Next
>> Hop
>> Label      Label      or Tunnel Id     Switched
>> interface
>> 35         16         172.2.142.0/24[V] <http://172.2.142.0/24%5BV%5D>   \
>>                                       0             Et0/0.27   2.2.27.2
>> 
>> 
>> See below the MPLS forwarding table of R8
>> RP/0/0/CPU0:R8#sh mpls forwarding
>> Mon Jul 14 00:58:38.436 UTC
>> Local  Outgoing    Prefix             Outgoing     Next Hop
>> Bytes
>> Label  Label       or ID              Interface
>> Switched
>> ------ ----------- ------------------ ------------ ---------------
>> ------------
>> 16000  Pop         2.2.0.7/32         Gi0/0/0/0.78 2.2.78.7
>> 39344
>> 16001  Pop         2.2.79.0/24        Gi0/0/0/0.78 2.2.78.7
>> 0
>> 16002  Pop         2.2.27.0/24        Gi0/0/0/0.28 2.2.28.2
>> 0
>>       Pop         2.2.27.0/24        Gi0/0/0/0.78 2.2.78.7
>> 0
>> 16003  Pop         2.2.0.9/32         tt89         2.2.0.9
>> 0
>> 16004  Pop         2.2.0.2/32         Gi0/0/0/0.28 2.2.28.2
>> 15126
>> 16005  Pop         2.2.29.0/24        Gi0/0/0/0.28 2.2.28.2
>> 0
>> 16007  16          172.2.0.1/32[V] <http://172.2.0.1/32%5BV%5D>
>> 2.2.0.7         12053
>> 16008  Pop         172.2.0.3/32[V] <http://172.2.0.3/32%5BV%5D>
>> 172.2.38.3      0
>> 16009  Aggregate   172.2.38.0/24[V] <http://172.2.38.0/24%5BV%5D>
>> ABC                          0
>> 16010  16011       172.2.0.5/32[V] <http://172.2.0.5/32%5BV%5D>
>> 2.2.0.9         0
>> 16011  16014       172.2.0.12/32[V] <http://172.2.0.12/32%5BV%5D>
>> 2.2.0.9         0
>> 16012  17          172.2.0.14/32[V] <http://172.2.0.14/32%5BV%5D>
>> 2.2.0.2         0
>> 16013  26          172.2.17.0/24[V] <http://172.2.17.0/24%5BV%5D>
>> 2.2.0.7         0
>> 16014  16007       172.2.59.0/24[V] <http://172.2.59.0/24%5BV%5D>
>> 2.2.0.9         0
>> 16015  16018       172.2.126.0/24[V] <http://172.2.126.0/24%5BV%5D>
>> 2.2.0.9         0
>> 16016  16          172.2.142.0/24[V] <http://172.2.142.0/24%5BV%5D>
>> 2.2.0.2         0
>> 16017  Unlabelled  172.2.38.8/32[V] <http://172.2.38.8/32%5BV%5D>
>> point2point     0
>> 
>> 
>> Debug out on R8
>> RP/0/0/CPU0:Jul 14 00:45:34.700 : netio[309]: mpls_get_payload_start:
>> ipv4: src=172.2.0.1, dst=172.2.0.3
>> RP/0/0/CPU0:Jul 14 00:45:34.700 : netio[309]: mpls_get_payload_start: src.
>> port = 0x56bb, dst. port = 0xb3, protocol = 0x6
>> RP/0/0/CPU0:Jul 14 00:45:34.700 : netio[309]: mpls_switch:
>> GigabitEthernet0_0_0_0.78, mpls eos 1, ttl 254, len 66, inlabel 16008,
>> tbl_id=0xe0000007, vrf_id=0x60000007 in=0x1300
>> RP/0/0/CPU0:Jul 14 00:45:34.700 : netio[309]: [mpls_switch:2773] Pkt Drop:
>> mpls_switch: GigabitEthernet0_0_0_0.78, No LFIB entry found for in_label
>> 16008
>> 
>> 
>> 
>> Config R8
>> RP/0/0/CPU0:R8#sh runn router bgp
>> Mon Jul 14 01:00:07.940 UTC
>> router bgp 2
>> address-family ipv4 unicast
>> !
>> address-family vpnv4 unicast
>> !
>> neighbor 2.2.0.9
>>  remote-as 2
>>  update-source Loopback0
>>  address-family vpnv4 unicast
>>  !
>> !
>> vrf ABC
>>  rd 2:2
>>  address-family ipv4 unicast
>>   allocate-label all
>>  !
>>  neighbor 172.2.38.3
>>   remote-as 123
>>   address-family ipv4 unicast
>>    send-community-ebgp
>>    route-policy PERMIT_ALL in
>>    route-policy PERMIT_ALL out
>>    send-extended-community-ebgp
>>   !
>>   address-family ipv4 labeled-unicast
>>    route-policy PERMIT_ALL in
>>    route-policy PERMIT_ALL out
>>    as-override
>>    send-extended-community-ebgp
>>   !
>>  !
>> !
>> !
>> RP/0/0/CPU0:R8#sh runn mpls
>> Mon Jul 14 01:00:13.759 UTC
>> mpls traffic-eng
>> interface GigabitEthernet0/0/0/0.28
>> !
>> interface GigabitEthernet0/0/0/0.78
>> !
>> !
>> mpls ldp
>> router-id 2.2.0.8
>> interface GigabitEthernet0/0/0/0.28
>> !
>> interface GigabitEthernet0/0/0/0.78
>> !
>> !
>> RP/0/0/CPU0:R8#
>> 
>> Thanks in advance for helping me understand this better
>> 
>> Maarten
> 
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Received on Wed Sep 24 2014 - 00:36:42 ART

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